EP2391695B1 - Integrated oxidation, reduction, and gasification method for producing a synthetic gas and energy in a chemical loop - Google Patents

Description

Given the climatic changes observed over the last decades and those foreseeable in the long term, the control of greenhouse gas emissions is becoming an increasingly demanding requirement for all economic sectors, and in particular those concerning the production of greenhouse gases. energy. One of the possible ways to control greenhouse gas emissions to the atmosphere is carbon capture and sequestration. This option is especially adapted in the case of the centralized use of fossil energies. Most of the solutions envisaged induce a significant energy penalty, with a self-consumption of the order of 20 to 30%.

Among the means for capturing CO ₂ in combustion units, the chemical loop, which is under development and which can be classified in the oxyfuel combustion category, has the advantage of producing combustion fumes. free of nitrogen from combustion air.

Thus, assuming that the gas, the solid and the liquid burn completely with oxygen supplied by particles such as metal oxides, the fumes would consist only of CO ₂ and water vapor, which, once cooled, below 100 ° C and free of condensed water, would consist of pure CO _{2 that} can be sequestered.

Chemical Looping Combustion (CLC) offers significant potential for energy efficiency and cost reduction. This process avoids the energy penalty related to the separation of oxygen from the air. It is based on the oxygen transfer capacity of certain materials such as metal oxides. An air reactor is used to oxidize the oxygen carriers prepared in the form of fine particles which are then transferred into a fuel reactor where they are reduced by fuel combustion. This process is generally imagined and carried out on a pilot scale in the form of two fluidized beds exchanging solids streams: the air reactor then being a fast fluidization type reactor at the top of which the flow of oxygen-depleted air and the particles are separated by a cyclone, the particles descending by gravity in the fuel reactor consists of a dense fluidized bed, where an overflow performs the reinjection of the solids at the bottom of the riser, while the combustion gases composed mainly of CO ₂ and H ₂ O are evacuated by the sky from this dense fluidized bed. When the oxygen stoichiometry is in excess of the requirements required to drive the combustion, the chemical loop allows for a total combustion of the fuel and produce fumes containing mainly CO ₂ while maximizing the energy produced. By limiting the supply of oxygen, for example by controlling the circulation of the oxidizing masses, it is also possible to achieve a partial combustion of the fuel and to produce fumes consisting at least in part of a mixture CO, H2 which, after treatment and downstream purification, can be used as a load for processes of transformation or energy production. This partial combustion limits energy production, but then makes it possible to recover the fumes produced containing hydrogen.

Prior art

Chemical loop integration tests in hydrocarbon conversion plants have been implemented.

The Patent FR 2,850,156 describes the principle of chemical loop combustion in a process dedicated to coal combustion.

The document US 2007/703526 discloses an improvement of the chemical loop in an integrated combustion oil hydrocarbon conversion facility for CO2 capture, comprising a catalytic cracking reactor in the presence of fluidized catalysts and a regenerator of the coke combustion catalysts deposited thereon. The regenerator is an oxygen carrier reduction reactor, and is fed with solid fuel and / or also petroleum residues comprising catalysts provided with coke. The reduction reactor is associated with an oxidation reactor. The oxygen carrier circulates between the two reactors. The reduction reactor is a circulating fluidized bed, which is fluidized with water vapor and / or recycled CO ₂ and / or SO 2. This patent describes a process with an arrangement of three reactors. However, the oxidizing masses only circulate between two reactors and the objective is the total combustion of the fuel.

The document W02007 / 082089A2 consists of a three-step process that highlights the use of metal oxide recirculation for hydrogen production. In a first reactor, a total combustion of the fuel makes it possible to produce CO2, H2O. The production of hydrogen is carried out by reoxidation of the metal oxide with steam. This embodiment imposes significant steam flows and therefore the need to heat and evaporate a large amount of water before introduction into the oxidation reactor, resulting in limits in the energy balance.

The production of hydrogen can be carried out by gasification: the patent application W02008 / 036902 describes, for example, a hydrocarbon gasification process, which is carried out in a conventional arrangement of two reaction zones. However, a problem faced by a person skilled in the art wanting to produce synthesis gas (hence hydrogen) by gasification is the kinetics of the reactions that take place in the gasification reactor as well as the high temperatures of reactions in the reactor gasification. The required residence time of the reagents is therefore important. This directly affects the sizes of the installations and more specifically the sizes of the reactors involved, which entails high investment costs.

Description of the invention

The present invention makes it possible to solve most of the disadvantages mentioned above and proposes an optimized integrated process in terms of energy cost and equipment, for the simultaneous production of synthesis gas and energy.

The invention is based on the production of the synthesis gas in a gasification reaction zone situated between the air reactor (or oxidation reaction zone) and the fuel reactor (or reduction reaction zone), by using the catalytic capacity of the metal oxides to lower the temperature as well as the endothermicity of the gasification and increase the rate of reactions favoring the production of a concentrated H2 / CO mixture at the outlet.

The air reactor R1 is used here to oxidize the reduced metal oxides and provide energy in an amount at least equal to the energy required for the activation of the reduction and gasification reactions. no production of synthesis gas or hydrogen is produced in this reactor.

The reduction and gasification reactions take place in two distinct reaction zones of the chemical loop of the process according to the invention, respectively R2 and R3.

Furthermore, the use of the catalytic capacity of the oxygen carriers and, more specifically, the metals they contain makes it possible to accelerate the kinetics of the reactions that take place in the gasification reactor and to reduce the reaction temperatures in the reactor. the gasification reactor, by decreasing the activation energy. The necessary residence time of the reagents is reduced. This directly affects the size of the plants and more specifically the reactor sizes involved. The reduction of the operating temperatures in the gasification reactor induces a better energy balance and a reduction of the investment costs due to the lowering of the constraints. thermo-mechanical on materials.

Summary of the invention

• a) on effectue l'oxydation des oxydes métalliques réduits MeO1-x dans une zone réactionnelle d'oxydation R1 alimentée par de l'air ;
• b) on effectue la combustion d'une charge hydrocarbonée solide et/ou liquide et/ou gazeuse par réduction au moins partielle des oxydes métalliques MeO dans une zone réactionnelle de réduction R2 pour produire un mélange gazeux CO2/H2O ;
• c) on effectue la gazéification catalytique d'une charge hydrocarbonée solide et/ou liquide au moyen des oxydes métalliques au moins partiellement réduits issus de R2 dans une zone réactionnelle de gazéification R3 pour produire un gaz de synthèse CO+H2;

et dans lequel l'énergie dégagée par l'oxydation des oxydes métalliques dans la zone réactionnelle d'oxydation R1 permet l'activation des réactions de gazéification et de réduction.The invention relates to a method for producing synthesis gas in at least one chemical loop comprising at least three distinct reaction zones of oxidation, reduction, gasification, in which:

• a) the oxidation of the reduced metal oxides MeO1-x is carried out in an oxidation reaction zone R1 supplied with air;
• b) the combustion of a solid and / or liquid and / or gaseous hydrocarbon feedstock is carried out by at least partial reduction of the metal oxides MeO in a reduction reaction zone R2 to produce a gaseous CO 2 / H 2 O mixture;
• c) the catalytic gasification of a solid hydrocarbon feedstock and / or liquid by means of the at least partially reduced metal oxides from R2 in a gasification reaction zone R3 to produce a CO + H2 synthesis gas;

and wherein the energy evolved by the oxidation of the metal oxides in the oxidation reaction zone R1 allows activation of the gasification and reduction reactions.

The two reaction zones R2 and R3 may be located in two separate reactors, or be two separate reaction zones in the same reactor. The oxygen O 2 necessary for the gasification can be provided at least partly by the metal oxides when they are partially reduced and / or by supplying the gaseous CO 2 / H 2 O mixture coming from the reduction reaction zone R2.

In one embodiment, exportable surplus energy is recovered by heat exchange within the reaction zones or on the gaseous effluents.

In the case where the feedstock supplying the gasification zone R3 is a solid feedstock, separation between the ashes and the metal oxide particles from the gasification zone R3 is advantageously effected and the reduction zone R1 is fed with the particles. of separate metal oxides.

In one embodiment, at least a portion of the CO + H2 synthesis gas produced in the gasification zone R3 is introduced into the reduction reactor.

In a variant of the process, at least a portion of the CO + H2 synthesis gas produced in the gasification zone R3 and at least a portion of the water coming from the condensation of the CO2 + H2O stream from the combustion zone R2 feed a WGS water gas shift unit to produce CO ₂ + H2.

In another variant, the gases produced in the gasification zone are, after purification, intended to feed at least partly a fuel cell.

In a last variant, the gases produced in the gasification zone are, after purification, intended to feed at least in part a Fischer Tropsch type hydrocarbon synthesis unit or a methanol synthesis unit or a dimethyl ether synthesis unit. .

Detailed description of the invention

The invention relates to an integrated oxidation, reduction and gasification process for the production of synthesis gas in a chemical loop.

This optimized method of chemical looping combustion (or CLC: Chemical Looping Combustion) is suitable for the combustion of liquid hydrocarbons and especially heavy and / or extra-heavy residues or bituminous and includes a gasification of liquid or solid fuels, which allows the production, simultaneous or not, of hydrogen (or synthesis gas) and energy in the same chemical loop. Energy production may be limited to the energy needs of the chemical loop (energy self-sufficiency), or exceed these needs and allow external valorization of the excess energy produced.

Principle of chemical looping combustion

Chemical loop combustion involves contacting a hydrocarbon feedstock with a metal oxide at a high temperature. The metal oxide then gives up some of the oxygen it contains, which participates in the combustion of hydrocarbons. At the end of this combustion, the fumes mainly contain carbon oxides, water and possibly hydrogen. Indeed, it is not necessary to put the air in contact with the hydrocarbon and the smoke is therefore mainly composed of combustion gases and possibly a dilution gas used for the transport and fluidization of the particles (by example of water vapor). It is thus possible to produce fumes that are mostly free of nitrogen and contain high CO ₂ contents (greater than 90% by volume), making it possible to envisage capture and then storage of CO ₂ . The metal oxide that participated in the combustion is then transported to another reaction chamber where it is brought into contact with air to be reoxidized. If the particles returning from the combustion zone are fuel-free, the gases coming from this reaction zone are predominantly free of CO ₂ -which is then only present in trace amounts, for example at concentrations below 1 to 2% by volume - and consists essentially of oxygen-depleted air, following the oxidation of the metal particles.

The charges that can be used for the chemical loop combustion are generally hydrocarbons (natural gas, liquid petroleum charges, preferably petroleum residues characterized by the fact that less than 10% of these residues have their boiling point under the conditions atmospheric concentrations above 350 ° C, or conversion residues, generally from hydroconversion processes or asphalts, residues of the deasphalting process, or solid charges such as coal or coke from coking processes).

The implementation of a chemical loop combustion process requires large quantities of metal oxides in contact with the fuel. These metal oxides are generally either contained in ore particles or in particles resulting from industrial processes (residues of the iron and steel or mining industry, catalysts of the used chemical or refining industry). It is also possible to use synthetic materials such as, for example, alumina or silica-alumina supports on which metals which can be oxidized (nickel oxide, for example) have been deposited.

The metal oxides that can be used to carry out the chemical loop combustion are generally oxides of Fe, Ti, Ni, Cu, Mg, Mn, Co, V, used alone or as a mixture. These metals may be in the form of natural ores (such as ilmenite) or deposited on a synthetic support or spent catalyst. Preferably, these solids are packaged in the form of powder, Sauter diameter preferably between 30 and 500 microns, and grain density of between 1400 and 8000 kg / m3, preferably between 1400 and 5000 kg / m3.

From one metal oxide to another, the quantity of oxygen theoretically available varies considerably and can reach high values close to 30%. Depending on the materials however, the maximum oxygen capacity actually available generally does not exceed more than 20% of the oxygen present. The ability of these materials to yield oxygen thus does not exceed globally not more than a few percent by weight of the particles and varies considerably from one oxide to another, generally from 0.1 to 15%, and often from 0 to 15%. , 3 and 13% by weight. The use of a fluidized bed is therefore particularly advantageous for conducting combustion. In fact, the finely divided oxide particles circulate more easily in the combustion and oxidation reaction chambers, and between these enclosures, if the particles are given the properties of a fluid (fluidization).

An oxygen carrier is characterized by its oxygen transport capacity, that is to say the amount of oxygen that this carrier will be able to exchange with the reaction medium between its most oxidized state and the least reversibly oxidized state. X is defined as the fraction of the total oxygen transfer capacity remaining in the oxide and ΔX as a fraction of the total oxygen transfer capacity. An oxygen carrier is a solid which, in addition to its capacity to transport oxygen, will be able to spontaneously release its oxygen in gaseous form into the reaction medium without the latter being necessarily reducing.

Chemical loop combustion is used to produce energy, in the form of steam or electricity, for example. The heat of combustion of the load is similar to that encountered in conventional combustion. This corresponds to the sum of the heats of reduction and oxidation in the chemical loop. The distribution between the heats of reduction and oxidation strongly depends on the metal oxides used to drive the combustion by chemical loop. In some cases, exothermicity is distributed between oxidation and metal reduction. In other cases, the oxidation is highly exothermic and the reduction is endothermic. In all cases, the sum of the oxidation and reduction heats is equal to the heat of combustion of the fuel. The heat is extracted by exchangers located inside, on the wall or in the appendix of the combustion and / or oxidation chambers, on the flue gas lines, or on the metal oxide transfer lines.

General description of the integrated process according to the invention

The integrated process according to the invention allows the simultaneous production of synthesis gas and energy in the same chemical loop.

The process according to the invention is carried out in at least one chemical loop comprising at least three distinct reaction zones of oxidation R1, reduction R2 and gasification R3.

Advantageously, to allow external energy recovery, the energy released by the oxidation of the metal oxides in the oxidation reaction zone R1 is greater than the sum of the energies required for the gasification and reduction reactions which occur respectively in the zone. R3 gasification and the reduction zone R2.

1. 1. au moins une zone réactionnelle d'oxydation R1, alimentée par de l'air, dite réacteur "air", où se déroule la réaction d'oxydation des oxydes métalliques après réduction,
2. 2. au moins une zone réactionnelle de réduction par combustion R2, dite réacteur "fioul" où se déroule la réaction de combustion des charges en présence de l'oxygène présent dans les oxydes métalliques,
3. 3. au moins une zone réactionnelle de gazéification R3, dite "réacteur de gazéification", des charges solides et/ou liquides pour un produire un gaz de synthèse, ladite gazéification étant catalysée par les oxydes métalliques au moins partiellement réduits issus de R2.

The chemical loop allowing the implementation of the process according to the invention comprises three distinct reaction zones:

1. 1. at least one air-supplied oxidation reaction zone R1, called the "air" reactor, where the oxidation reaction of the metal oxides takes place after reduction,
2. 2. at least one combustion reduction reaction zone R2, called "fuel" reactor, where the combustion reaction of the charges takes place in the presence of the oxygen present in the metal oxides,
3. 3. at least one gasification reaction zone R3, called a "gasification reactor", solid and / or liquid charges for producing a synthesis gas, said gasification being catalyzed by the at least partially reduced metal oxides from R2.

• 4. un ou plusieurs organes de séparations particules - gaz (cyclone)
• 5. un ou plusieurs organes d'étanchéité dans les conduits de liaison entre chacun des réacteurs permettant la circulation des oxydes métalliques (tel que par exemple des dispositifs tels que des siphons)
• 6. dans le cas de la gazéification des combustibles solides au moins un organe de séparation entre les particules d'oxyde métalliques et les particules de nature différente (cendres, imbrûlés) nécessaire entre le réacteur de gazéification et le réacteur air pour éviter un mélange possible de CO₂ avec l'azote dans le réacteur air.

The chemical loop device may also include:

• 4. one or more particle-gas separation members (cyclone)
• 5. one or more sealing members in the connecting ducts between each of the reactors allowing the circulation of the metal oxides (such as for example devices such as siphons)
• 6. in the case of gasification of solid fuels at least one separating member between the metal oxide particles and the particles of different nature (ash, unburnt) required between the gasification reactor and the air reactor to avoid possible mixing of CO ₂ with the nitrogen in the air reactor.

In a variant of the process, it is possible to carry out the gasification reaction and the reduction reaction in the same reactor in two separate reaction zones.

In the process according to the invention, the energy released by the oxidation of the oxygen carrier in the "air reactor" R1 is at least equal to the sums of the energies required for the gasification and reduction reactions: thus, the energy released by the oxidation of the oxygen carrier in the "air reactor" R1 can provide the energy required for the activation of the gasification reactions (R3) and reduction (R2), but also to possibly provide a usable energy both in the process and from the point of view of energy production to the outside (heat and / or electricity).

In the particular case in which synthesis gas is supplied to the reduction reactor, the reactions in this reactor become exothermic, thus favoring the overall energy balance of the chemical loop.

List of Figures

The process of the invention is illustrated by way of nonlimiting Figures 1 to 5 .

The figure 1 represents the sequence of circulation of solids between the reaction zones (in this case constituted by reactors).

A flow rate of metal oxides flows from the oxidation reactor (or "air reactor") (R1) supplied with air via a line (1) to the reduction reactor (or "oil reactor") (R2) where the reaction takes place. combustion of the charge by reduction of the MeO oxygen-carrying materials in their maximum oxidation state, that is to say 0.8 ≤ X ≤ 1 and preferably 0.95 ≤ X ≤ 1, for a specific duration generally from 1 to 15 minutes. The metal oxides at the outlet of the reduction reactor R2 (MeO _1-x ) are partially in metallic form, with 0 ≤ X ≤ 0.5 and preferably 0 ≤ X ≤ 0.1, after reaction between the oxygen existing in their structure and the solid and / or liquid and / or gaseous fuel arriving via a line (2). These reduced forms MeO _1-x metal oxides circulate through a line (3) of the fuel reactor (R2) to the gasification reactor (R3) where a gasification reaction of a solid and / or liquid fuel arriving via a line ( 4) takes place. This gasification step is catalyzed by the reduced metal oxides MeO _{1-x '} for which 0 ≤ X ≤ 0.5, and preferably 0 ≤ X ≤ 0.1. The gasification reactor is fed with an oxidizing gas such as CO ₂ or H ₂ O and / or a mixture H ₂ O, CO ₂ originating at least in part from the combustion reaction taking place in the reactor R2. The gasification reactor (R3) is thus supplied by a line (5) with at least a portion of the CO ₂ , H ₂ O and / or the CO ₂ / H ₂ O mixture coming from the stack of the reduction reactor (R2) . The remaining portion of the CO ₂ , H ₂ O and / or CO ₂ / H ₂ O mixture is sent via a line (6) to a condenser C to separate the CO ₂ from the water. The water thus separated can thus supply a line (7) with a WGS water gas shift unit which makes it possible to produce a CO2 / H2 mixture from the synthesis gas arriving via a line (8) from the reactor R3. At the outlet of the reactor R3, the solid particles are sent via a line (10) to a separator S in order to separate the ashes from the metal oxides MeO _{1 -x} which are sent to the reactor R1.

The device can also be completed by sulfur treatment units in H ₂ S and / or SO _{2 form} if the fuel contains sulfur as well as a CO ₂ - H ₂ separation unit. These devices are not shown in the figures. Depending on the destination of the gases from the process, the gases will be purified to desulphurize the fumes using the methods known to those skilled in the art to achieve the specifications required for downstream applications of the process described in the invention.

In the so-called "reactor fuel" reactor R2, is carried out the reduction of materials known as "oxygen-carrying materials" by contact between the materials and the liquid fuel and / or gas and / or solid arriving via line (2).

In the so-called "gasification reactor" R3, the gasification of a liquid or solid residue (for example) which is recovered in the form of synthesis gas is carried out. CO / H2 at conditions (temperature, pressure, number of moles of water per mole of fuel) required for gasification and in the presence of reduced MeO _{1-x materials} which have catalytic properties.

In the so-called "air reactor" reactor R1, the reduced MeO _{1-x materials} are oxidized by air, so as to return to their most oxidized state for which 0.8 ≤ X ≤ 1.0, and preferably 0, 95 ≤ X ≤ 1.

The figure 2 represents a use of the process according to the invention in which the stream (8) from R3 is sent to a Fischer-Tropsch FT unit in order to produce an HC hydrocarbon stream. In this case the water from the condenser C is evacuated by the line (7).

The figure 3 represents a variant of the process described on the figure 1 wherein a portion of the stream from the WGS water gas shift unit feeds a PC fuel cell. Possibly part of the synthesis gas from reactor R3 via line (8) also feeds the fuel cell to produce electricity and / or heat.

The figure 4 represents the configuration in which the gasification reaction and the reduction reaction are carried out in the same reactor, in two separate reaction zones R3 and R2.

In this configuration, the oxidizing mass in its most oxidized form (12) enters the reduction zone R2 where it is brought into contact with the gases (19) coming from the zone R3 containing at least partly a mixture (CO, H2 ) which will be oxidized to CO2, H2O. The oxidizing masses will also complete the combustion of hydrocarbons from the zone R3 present in the gas phase (19). The fumes of R2 are discharged through a conduit (16) and essentially contain water and CO2. The water can then be condensed and the CO ₂ sent transported to a storage place after a possible post-treatment allowing for example to purify the CO ₂ by desulfurizing the fumes.

The oxidizing masses of the zone R2 are then directed to the zone R3 in which the combustion of the fuel (4) is carried out by the lines (15) or (14). Part of the oxidizing masses may optionally be returned to the air reactor (R1).

One of the features of the invention consists in arranging the zones R2 and R3 one above the other. It is then possible thanks to particular devices to allow all the gases from R3 to pass into R2 and the solids from R2 to flow into R3 so that the fuel contacts the counter-current oxidizing mass as represented on the figure 4 . These particular devices well known to those skilled in the art are for example internal such as perforated plates or baffles.

The solid from R3 is recycled to R1 by the line (20).

The figure 5 represents the process according to the invention in the same configuration as the figure 1 , in the case of the example given below.

Operating conditions

Advantageously, the reactions in the "air" (R1), fuel (R2) and gasification (R3) reactors take place at a temperature of between 700 ° C. and 1200 ° C., very preferably between 750 and 950 ° C.

The residence time of the metal oxides in the fuel reactor (R2) depends on the nature of the fuel and can be estimated generally between 30 s and 10 minutes, preferably between 1 and 8 minutes.

The residence time of the metal oxides in the air reactor (R1) depends on the oxidation state and / or reduction of these oxides and can be estimated generally between 30 seconds and 10 minutes, preferably between 1 and 3 minutes. .

The residence time of the metal oxides in the gasification reactor depends on the nature of the fuel to be gasified and can be estimated generally between 1 and 20 minutes, preferably between 1.5 minutes and 10 minutes.

Specific advantages

Several specific advantages of the method according to the invention are cited below, without limitation.

The invention makes it possible, by using chemical looping oxidizing masses, to combine the production of energy and the production of hydrogen (or more generally of synthesis gas) in the same chemical loop.

The chemical loop of the process according to the invention makes it possible not only to produce the energy necessary for the production of synthesis gas, but possibly also to produce exploitable energy in the form of heat and / or electricity.

Furthermore, in a particular embodiment of the invention, the optional addition of a portion of the synthesis gas produced in the gasification reactor to the reduction reactor induces exothermic reactions in this reactor, further promoting the balance. overall energy efficiency of the invention ( Figure 1 , (11)).

The process according to the invention allows the use of the catalytic capacity of the reduced metal oxides at the outlet of the reduction reactor (R2) in the gasification reaction (R3). The gasification reaction is thus catalyzed by the metal oxides, without external catalyst supply.

Moreover, the process according to the invention makes it possible to inject heavy charges directly into contact with the oxygen carrier in the reduction reactor ("fuel reactor" R2).

The integrated method according to the invention finally makes it possible to avoid residence times of the solid fuels / metal oxides important in the reduction reactor ("reactor fuel") which are generally of the order of 15 to 20 minutes. Indeed, these residence times are important and usually involve large size reactors.

EXAMPLE

• dans le réacteur dit "réacteur fuel", s'effectue la réduction des matériaux dits "matériaux transporteur d'oxygène" par contact entre les matériaux et un combustible liquide et/ou gaz et/ou solide.
• dans un réacteur distinct, dit "réacteur de gazéifcation", s'effectue la gazéification d'un combustible (un résidu liquide ou solide, à titre d'exemple) qui est valorisé sous forme de gaz de synthèse aux conditions (T et P, nombre de moles d'eau pour 1 mole de combustible) de gazéification et en présence des matériaux réduits qui ont des propriétés catalytiques.
• dans le réacteur dit "réacteur air", les matériaux réduits seront oxydés par l'air.

The example below (shown on the figure 5 ) implements the principle of operation on three separate reactors of the present invention as shown in FIG. figure 1 :

• in the so-called "reactor fuel" reactor, is carried out the reduction of so-called materials "oxygen carrier materials" by contact between the materials and a liquid fuel and / or gas and / or solid.
• in a separate reactor, the so-called "gasification reactor", the gasification of a fuel (a liquid or solid residue, for example) which is valorised in the form of synthesis gas at the conditions (T and P, number of moles of water per 1 mole of gasification fuel and in the presence of reduced materials which have catalytic properties.
• in the reactor called "air reactor", the reduced materials will be oxidized by air.

In this example are calculated an energy balance and a material balance representing the energy equilibrium system, that is to say in a situation where the energy released by the oxidation of the oxygen carrier in the "air reactor" "is sufficient not only to activate the gasification and reduction reactions, but also to provide usable heat both in the process and from a heat production point of view.

The operating conditions considered at each stage are the following:

Gasification

1. 1) the gasification reaction is complete: CO and H ₂ are the unique products of the reaction.
2. 2) the fluidization parameters are not taken into account.
3. 3) Reagents are solid and / or liquid fuels and water vapor.
4. 4) the reaction is endothermic.

Reduction of the metal oxide

1. 1) The reduction reaction is complete with respect to the fuel. The products of the reaction are CO ₂ and H ₂ O.
2. 2) The exchange is ideal between the oxygen carrier and the liquid fuel: there is no diffusion limitation, no carbon formation, no loss of reactivity.
3. 3) the reaction is endothermic.

Oxidation of the metal oxide

• 7. The oxidation reaction is complete
• 8. ideal exchange between the oxygen carrier and the air
• 9. the reaction is exothermic

• la combustion du combustible liquide C₁₉H₃₀, qui constitue en première approche un cas similaire au fioul domestique;
• le choix de NiO comme transporteur d'oxygène, la réaction complète de réduction est alors :
  
          53NiO + C₁₉H₃₀ -> 19CO₂ + 15H₂O + 53Ni
  
  
• la forme réduite du transporteur d'oxygène comme étant Ni, la réaction complète d'oxydation est alors :
  
          Ni + 0,5O₂ → NiO
  
  
• la gazéification est menée à pression atmosphérique.

In a more particular way, the present example considers:

• the combustion of the liquid fuel C ₁₉ H ₃₀ , which constitutes at first approach a case similar to domestic fuel oil;
• the choice of NiO as oxygen carrier, the complete reduction reaction is then:
  
  53NiO + C ₁₉ H ₃₀ -> 19CO ₂ + 15H ₂ O + 53Ni
  
  
• the reduced form of the oxygen carrier as Ni, the complete oxidation reaction is then:
  
  Ni + 0.5O ₂ → NiO
  
  
• gasification is conducted at atmospheric pressure.

The system is considered to be in energy equilibrium, however the system has a dynamic character since the solid oxygen carrier circulates continuously between the different reactors of the system. In the calculations, we are interested in the evolution of the properties of the amount of solid oxygen carrier required for the conversion of 100 Nm ³ / h of vaporized liquid feed C ₁₉ H ₃₀ .

Numerical values: Heat of formation kJ.mol ^-1 ΔH _f (H ₂ O) -241.6 Δ H _f (CO ₂ ) -393.12 Δ H _f (CO) -110.5 ΔH _f (H ₂ ) 0 ΔH _f (O ₂ ) 0 ΔH _f (NiO) -240 ΔH _f (C ₁₉ H ₃₀ ) -640

In the fuel reactor

53NiO + C ₁₉ H ₃₀ -> 19CO ₂ + 15H ₂ O + 53Ni

ΔH _r (fuel) = 2266 kJ / mol _C19H30 = 52.7 kJ / mol _NIO

• dans les conditions stoechiométriques (C/O=0.36) $${\dot{n}}_{\mathit{NiO}}=53{\dot{n}}_{{\mathrm{<figure-callout\; id="19"\; label="C"\; filenames="imgf0004.png"\; state="\{\{state\}\}">C</figure-callout>}}_{19}{H}_{30}}=237\mathit{kmol}\mathrm{.}{h}^{-1}$$
  
  $${\dot{n}}_O={\dot{n}}_{\mathit{NiO}}=237\mathit{kmol}\mathrm{.}{h}^{-1}\mathit{soit}{\dot{m}}_O=M_O\mathrm{.}{\dot{n}}_O=3,792t\mathrm{.}{h}^{-1}$$
  
  
  ṁ_i le flux massique du composé i
  ṅ_i le flux massique du composé i
  M_i la masse molaire du composé i

Calculation of the amount of _NiO solid required to convert 100 Nm ³ / h of vaporized fuel:

• under stoichiometric conditions (C / O = 0.36) $${\dot{\mathrm{not}}}_{\mathit{NiO}}=53{\dot{\mathrm{not}}}_{{\mathrm{<figure-callout\; id="19"\; label="VS"\; filenames="imgf0004.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{19}{H}_{30}}=237\mathit{kmol}\mathrm{.}{h}^{-1}$$
  
  $${\dot{\mathrm{not}}}_O={\dot{\mathrm{not}}}_{\mathit{NiO}}=237\mathit{kmol}\mathrm{.}{h}^{-1}\mathit{is}{\dot{m}}_O=M_O\mathrm{.}{\dot{\mathrm{not}}}_O=3,792t\mathrm{.}{h}^{-1}$$
  
  
  ṁ _i the mass flow of the compound i
  ṅ _i the mass flow of the compound i
  M _i the molar mass of the compound i

puissance nécessaire à la conversion des 100 Nm³/h $$P_{\mathit{fuel}}={\dot{n}}_{C_{19}{H}_{30}}\cdot \mathrm{\Delta }{H}_r{\left(\mathit{fuel}\right)}_{C_{19}{H}_{30}}=2,81\mathit{MW}$$

With a RoDX (mobilizable oxygen mass per gram of catalyst) of 0.01 g / gNiO. $${\dot{m}}_{{\mathit{NiO}}_{\mathit{total}}}=\frac{{\dot{m}}_o}{\mathit{RoDX}}=379,2t\mathrm{.}{h}^{-1}$$

power required for the conversion of 100 Nm ³ / h $$P_{\mathit{fuel\; oil}}={\dot{\mathrm{not}}}_{{\mathrm{<figure-callout\; id="19"\; label="VS"\; filenames="imgf0004.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{19}{H}_{30}}\cdot \mathrm{\Delta }{H}_r{\left(\mathit{fuel\; oil}\right)}_{{\mathrm{VS}}_{19}{H}_{30}}=2,81\mathit{MW}$$

In the gasification reactor:

19H ₂ O + C ₁₉ H ₃₀ -> 19CO ₂ + 34H

Δ H _r (gasification) = 3130 kJ / mol _C19H30
power required for the conversion of 50 Nm ³ / h $$P_{\mathit{gas}}={\dot{\mathrm{not}}}_{{\mathrm{<figure-callout\; id="19"\; label="VS"\; filenames="imgf0004.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{19}{H}_{30}}\cdot \mathrm{\Delta }{H}_r{\left(\mathit{gasification}\right)}_{{\mathrm{<figure-callout\; id="19"\; label="VS"\; filenames="imgf0004.png"\; state="\{\{state\}\}">VS</figure-callout>}}_{19}{H}_{30}}=1.94\mathit{MW}$$

This value does not take into account the catalytic activity of the solid and represents a high estimate of the energy required for gasification.

In the air reactor:

Ni + 0.5O ₂ -> NiO

Δ H _r (oxidation) = -240 kJ / mol _NI
power provided by the regeneration of 65.7 mol / s of catalyst by oxidation: $$P_{\mathit{air}}={\dot{\mathrm{not}}}_{\mathit{Or}}\cdot \mathrm{\Delta }{H}_r{\left(\mathit{oxidation}\right)}_{\mathit{Or}}=-15,8\mathit{MW}$$

Balance sheet:

• P = - 6,7 MW _th pour une quantité de solide circulant de 379,2 t/h.

soit un rendement thermique de 25% (hors valorisation de l'H2 et du CO), calcul de rendement basé sur le PCI du fuel domestique (26,8 MW). La production d'hydrogène en parallèle est de 152 kg/h. Le différentiel de température entre la température du solide oxydé sortant du réacteur d'oxydation et la température du solide qui y entre partiellement réduit après utilisation de la chaleur est de l'ordre de 70°C pour une température maximale de l'ordre de 1100°C.The calculation thus detailed (see above) makes it possible to establish an energy balance of the reactions which take place in the various reactors of the invention. This balance only takes into account the heat of reactions. The overall balance taking into account the heats necessary to heat the reagents as well as recoverable heat on the fluids leaving the reactors involved, namely:

• P = - 6.7 MW _th for a circulating solid quantity of 379.2 t / h.

a thermal efficiency of 25% (excluding the valuation of H2 and CO), yield calculation based on the PCI of domestic fuel (26.8 MW). The hydrogen production in parallel is 152 kg / h. The temperature difference between the temperature of the oxidized solid leaving the oxidation reactor and the temperature of the solid which enters it partially reduced after use of the heat is of the order of 70 ° C. for a maximum temperature of the order of 1100 ° C. ° C.

Claims (10)

1. A method of producing syngas in at least one chemical loop comprising at least three distinct oxidation, reduction, gasification reaction zones, comprising:

   1. carrying out oxidation of the reduced metallic oxides MeO1-x in an air-supplied oxidation reaction zone R1 ;

   2. carrying out combustion of a solid and/or liquid and/or gaseous hydrocarbon feed through at least partial reduction of the metallic oxides MeO in a reduction reaction zone R2 so as to produce a gaseous CO₂/H₂O mixture ;

   3. carrying out catalytic gasification of a solid and/or liquid hydrocarbon feed by means of the at least partly reduced metallic oxides from R2 in a gasification reaction zone R3 so as to produce a CO + H₂ syngas ;
   and wherein the energy released through oxidation of the metallic oxides in oxidation reaction zone R1 allows the gasification and reduction reactions to be activated.
2. A method as claimed in claim 1, wherein the two reaction zones R2 and R3 are located in two distinct reactors.
3. A method as claimed in claim 1, wherein the two reaction zones R2 and R3 are two distinct reaction zones in a single reactor.
4. A method as claimed in any one of the previous claims, wherein the oxygen O₂ required for gasification is provided at least partly by the metallic oxides when they are partly reduced and/or by the CO₂/H₂O gaseous mixture from reduction reaction zone R2.
5. A method as claimed in any one of the previous claims, wherein the exportable excess energy is recovered by heat exchange within the reaction zones or on the gaseous effluents.
6. A method as claimed in any one of the previous claims wherein, in cases where the feed supplying gasification zone R3 is a solid feed, separation is performed between the ashes and the metallic oxide particles from gasification zone R3, and reduction zone R1 is supplied with the separated metallic oxide particles.
7. A method as claimed in any one of the previous claims, wherein at least part of the CO + H₂ syngas produced in gasification zone R3 is fed into the reduction reactor.
8. A method as claimed in any one of the previous claims, wherein at least part of the CO + H₂ syngas produced in gasification zone R3 and at least part of the water resulting from the condensation of the CO₂ + H₂O stream from combustion zone R2 supply a water gas shift unit WGS in order to produce CO₂ + H₂.
9. Use of the method as claimed in any one of claims 1 to 8, wherein the gases produced in the gasification zone are, after purification, intended to be fed at least partly into a fuel cell.
10. Use of the method as claimed in any one of claims I to 8, wherein the gases produced in the gasification zone are, after purification, intended to be fed at least partly into a Fischer-Tropsch type hydrocarbon synthesis unit or a methanol synthesis unit or a dimethylether synthesis unit.

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